HSBC agreed Tuesday to pay $1.9 billion to settle a U.S. money-laundering probe. Europe's largest bank will pay the biggest penalty ever imposed on a bank after facing accusations it transferred funds through the U.S. from Mexican drug cartels and on behalf of nations such as Iran that are under international sanctions.

From 2001 to 2010, British bank Standard Chartered conspired with Iran to hide roughly 60,000 transactions involving at least $250 billion. And when they were called out by New York regulators for the possibility that this might have been illegal, their response was blunt ... and profane.

Iran was largely cut off from global commerce on Thursday, when the company that handles financial transactions said it was severing ties with many Iranian banks %u2014 part of an international effort to discourage Tehran from developing nuclear weapons. The action is meant to enforce European Union sanctions, as global financial transactions are impossible without using SWIFT, and will go a long way toward isolating Iran financially.

Barclays agreed to pay $298 million to settle criminal charges that it did business with countries like Cuba, Iran, Libya and Sudan, violating U.S. economic sanctions against these nations. Barclays is just the latest in a string of banks that have transacted with such countries.